Just to play devil’s advocate on the military philosophy of the day.. circa 1940’s
Why have a dedicated torpedo bomber at all.. They were by definition a huge compromise that resulted in very high loses historically..
Your question revolves around a purist point of view, in that you consider tactical and performance as the defining characteristics for aircraft procurement. Of this was always going to be important, warfare being what it is when technical development becomes a miltary advantage.
What you don't address is the politics of aircraft procurement. These aircraft weren't designed by national governments, they were thought up by designers, either as their own initiatives or to meet requirements set by the miltary planners.
In Germany, the aircraft industry was very political indeed. Witness the rivalry between established clique-member Ernst Heinkel and wannabe member Willy Messerschmitt in the race to replace the Arado 68 as the frontline fighter. This competition wasn't about whose aircraft was best - both sides spread rumours about the others products - but about whose influence in high places was superior. Both men had fighter designs and were determined to sign a contract. In fact, the establishment at one point offered Messerschmitt a place as a university lecturer to try and stop him from causing a fuss.
Secondly, as mentioned above the aircraft companies sometimes seek to meet specifications issued by the military. In this period, multi-role aeroplanes were not usually considered, although there had been exceptions, and the problems in designing aircraft capable of all-round utility and retention of sufficient performance was difficult, to say the least. In most cases, aircraft were utilisied in multiple capacities during the first half of the war by circumstance, not design, as it was noticed that some aircraft were sufficiently capable to be considered for other roles.
We must also allow for the failure of a considerable number of designs to fail to meet the demands expected of them. Having built and purchased them, these aeroplanes were on strength and simply scrapping them made little economic sense, so they would be given secondary roles or adapted for them.
With some nations, the issue of torpedo bombing was more important than others. The naval nations, such as Britain, America, and Japan would naturally see the torpedo as an important part of their air strategy, thus ensure they had aircraft capable to fulfilling that role.
The Germans, despite their pretensions, were not a great naval nation in WW2. The limited coastline and poor defense of their naval assets was one reason why U-boats were so favoured, and even they were a poor relation to the army in Hitlers eyes. In fact, since the Luftwaffe was initially considered a supportive arm to the Wehrmacht as well, the need for torpedo bombers was minor, as bombs were considered a more direct means of anti-shipping missions and note the German preference for accurate dive bombing.
Only if the two German aircraft carriers had been completed would that need increase dramatically. Since German aircraft were profiled for bomb carrying, the larger torpedo was not so easily accomodated. I don't know if the Fiesler 167 was intended to carry them, but if that was the case, the obselescence of that design would quickly have made itself felt.
Yes, I know the Fairey Swordfish persisted in British hands, biut notice that attempts were made to replace it, and only the availability of engines delivering two or three times the power at the wars end made aeroplanes like the Blackburn Firebrand a realistic viable attempt at multi-role aeroplanes in naval air warfare (despite the fact that the Kriegsmarine had pretty well been defeated by then)
Further, we have to consider the length of time required to bring new aircraft into operation. The Germans frequently had prolongued aircraft development issues, mostly related to advanced features, as they attempted to create better warplanes than the enemy. Nonetheless, the prevarication and factional disputes of the German air ministry did not help the situation. After all, plenty of capable designs were dismissed and abandoned for no other reasons such as politics alone. The fact an aeroplane
might be capable is not reason enough to order. This capability must be earned - either with demonstration (such as Kurt Tanks illicit supply of Fw187's to units in Norway) or by reputation (such as the initial support for Heinkels He112).
Of course fictional aeroplanes are another matter, but I like this one because it makes sense. Adaption is easier than original design in many cases. and it assumes that the Kriegsmarine were keen to procure better carrier aircraft capable of performing the tasks that they would have needed in the light of experience rather than prewar doctrine.